Levels of society (6)
I believe the answer is:
strata
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">levels of society</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for strata that I've seen before include "Layers as of rocks in earth's crust" , "Layers as of rock in the earth's crust" , "Tiers of thicknesses" , "Layers into which rocks are divided" , "Geological layers" .)